The First Animals

THE FIRST ANIMALS

According to molecular clock data, the separation of the Animal Kingdom from the Plant Kingdom occurred 1609±60 Ma (2004HedgesSB_ShoeJL). Molecular estimates indicate that the last common ancestor of multicellular representatives of the fauna (Metazoa) was Neoproterozoic, most likely younger than 800 million years (2015PisaniD_LiuAG). Biomarkers of metazoan living systems identified in sedimentary deposits indicate their presence in the seas since the Cryogenian period (2018ZumbergeJA_SummonsRE), which began around approximately 720 Ma (2023CohenKM_CarN).

Multicellular animals were part of early Ediacaran ecosystems and are found below layers dated to 632.5 ± 0.5 Ma (2007Yin_LHuJ). The oldest fossil of a multicellular organism resembling a sponge (Porifera) is about 600 Ma (2015YinZ_TafforeauP). The last Neoproterozoic glaciation (about 582 Ma) coincides with the appearance of complex organisms in the fossil record (2007BowringSA_AllenPA). Evidence of burrowing by any animal larger than 1 cm is absent from rock layers formed before 575 Ma (2002ErwinDH_DavidsonEH). A diverse assemblage of fossilized bodies and tracks of bilateral organisms (Bilateria) have been found in deposits ranging in age from 558±1.0 to 555.3±0.3 Ma (2000MartinMW_KirschvinkJL; 2003GrazhdankinDV). The oldest protostomes (Protostomia) like mollusks with shells were given the name Kimberella (2007FedonkinMA_IvantsovAY).

Around 543 Ma, a complex community of soft-bodied bilaterians appears in the fossil record (1995GrotzingerJP_KaufmanAJ). The tracks of the first burrowing creations of the worm Treptichnus pedum are dated to the period 542-541 Ma (2007BowringSA_AllenPA). Perhaps 540 Ma, Saccorhytus coronarius, the founder of the line of deuterostomes (Deuterostomia), saw the light of day (2017HanJ_HuangH). In the group of bilaterally symmetrical animals, the phylum Chordates (1995ChenJY_ZhouGQ) emerged 525 Ma. This lineage laid the foundations for the creation of an internal skeleton and joints, in one of which ligamentum capitis femoris (LCF) was later formed.

Upper Vendian, Mezen Formation (about 555 Ma). Slab with imprints of transversely segmented organisms from the extinct type Proarticulata, showing traces of movement and feeding (fragment). Exposition of the Orlov Paleontological Museum (Moscow); photo by the author.

Ovatoscutum concentricum Glaessner et Wade. Vendian, Winter Coast of the White Sea. Collection of the Orlov Paleontological Museum (Moscow); photo by the author.

Brachiopods. Collection of the Orlov Paleontological Museum (Moscow); photo by the author.

Scheme of structure (A) and reconstruction (B) of the most ancient chordate Haikouella, early Cambrian, approx. 539 million years. Exposition of the Orlov Paleontological Museum (Moscow); photo by the author.

References

Hedges SB, Blair JE, Venturi ML, Shoe JL. A molecular timescale of eukaryote evolution and the rise of complex multicellular life. BMC evolutionary biology. 2004;4(1)1-9. [link.springer.com]

Pisani D, Liu AG. Animal evolution: only rocks can set the clock. Current Biology. 2015;25(22)R1079-81. [cell.com]

Zumberge JA, Love GD, Cárdenas P, Sperling EA, Gunasekera S, Rohrssen M, Grosjean E, Grotzinger JP, Summons RE. Demosponge steroid biomarker 26-methylstigmastane provides evidence for Neoproterozoic animals. Nature Ecology & Evolution. 2018;2(11)1709-14. [nature.com]

Cohen KM, Harper DAT, Gibbard PL, Car N. The International Commission on Stratigraphy (ICS) International Chronostratigraphic Chart. September 2023. [stratigraphy.org]

Yin L, Zhu M, Knoll AH, Yuan X, Zhang J, Hu J. Doushantuo embryos preserved inside diapause egg cysts. Nature. 2007;446(7136)661-3. [ui.adsabs.harvard.edu , academia.edu]

Yin Z, Zhu M, Davidson EH, Bottjer DJ, Zhao F, Tafforeau P. Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian. Proceedings of the National Academy of Sciences. 2015;112(12)E1453-60. [pnas.org]

Bowring SA, Grotzinger JP, Condon DJ, Ramezani J, Newall MJ, Allen PA. Geochronologic constraints on the chronostratigraphic framework of the Neoproterozoic Huqf Supergroup, Sultanate of Oman. American Journal of Science. 2007;307(10)1097-145. [ajsonline.org]

Erwin DH, Davidson EH. The last common bilaterian ancestor. Development. 2002;129(13)3021-32. [journals.biologists.com]

Martin MW, Grazhdankin DV, Bowring SA, Evans DA, Fedonkin MA, Kirschvink JL. Age of Neoproterozoic bilaterian body and trace fossils, White Sea, Russia: implications for metazoan evolution. Science. 2000;288:841-5. [science.org]

Гражданкин ДВ. Строение и условия осадконакопления вендского комплекса в Юго-Восточном Беломорье. Стратиграфия. Геологическая корреляция. 2003;11(4)3-23. [repository.geologyscience.ru]

Fedonkin MA, Simonetta A, Ivantsov AY. New data on Kimberella, the Vendian mollusc-like organism (White Sea region, Russia): palaeoecological and evolutionary implications. Geological Society, London, Special Publications. 2007;286(1)157-79. [lyellcollection.org]

Grotzinger JP, Bowring SA, Saylor BZ, Kaufman AJ. Biostratigraphic and geochronological constraints on early animal evolution. Science. 1995;270:598-604. [science.org]

Han J, Morris SC, Ou Q, Shu D, Huang H. Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China). Nature. 2017;542(7640)228-31. [nature.com]

Chen JY, Dzik J, Edgecombe GD, Ramsköld L, Zhou GQ. A possible Early Cambrian chordate. Nature. 1995;377(6551)720-2. [nature.com]

The original text in Russian is available at the link: Первые животные

NB! Fair practice / use: copied for the purposes of criticism, review, comment, research and private study in accordance with Copyright Laws of the US: 17 U.S.C. §107; Copyright Law of the EU: Dir. 2001/29/EC, art.5/3a,d; Copyright Law of the RU: ГК РФ ст.1274/1.1-2,7

BLOG CONTENT

13.8-0.5 Bya

Comments

THE GIFTS OF THE MAGI FOR ORTHOPEDIC SURGEONS

Translation of the article: Архипов СВ. Новая техника проксимального крепления при реконструкции ligamentum capitis femoris: Дары волхвов ортопедическим хирургам. The text in Russian is available at the following link: 2026АрхиповСВ . A Novel Technique for Proximal Fixation of Ligamentum Capitis Femoris Reconstruction: The Gifts of the Magi for Orthopedic Surgeons S.V. Arkhipov, Independent Researcher, Joensuu, Finland CONTENT [i] Abstract [ii] Introduction [iii] Materials and Methods [iv] Technique [v] Discussion [vi] Conclusion [vii] Appendix [viii] References [ix] Structured Abstract [x] Additional material [i] Abstract An experimental technique for reconstruction of the ligamentum capitis femoris (ligamentum teres femoris) is described. The proposed method involves creating two portions of the ligament analog: a pubic portion and an ischial portion. Fixation of thes...

2018YoussefAO

Content [i] Annotation [ii] Original text [iii] References [iv] Source & links [v] Notes [vi] Authors & Affiliations [vii] Keywords [i] Annotation Abstract of the article: Youssef AO. Medial approach open reduction with ligamentum teres partial excision and plication for the management of congenital hip dislocation (2018). The article describes a method for transposition of the proximal attachment of the ligamentum capitis femoris (LCF) in congenital hip dislocation. The text in Russian is available at the following link: 2018YoussefAO . [ii] Original text Abstract Because of the known tendency for early redislocation following open reduction, we developed surgical methods for shortening the ligamentum teres to improve immediate postoperative stability when performing medial approach open reduction (MAOR) for the management of developmental dysplasia of the hip. Between 2004 and 2014, 32 patients w...

2008WengerDR_MiyanjiF

Article: Wenger DR et al. Ligamentum teres maintenance and transfer as a stabilizer in open reduction for pediatric hip dislocation: surgical technique and early clinical results (2008). The article describes a method of open reconstruction of the ligamentum capitis femoris (LCF) for hip dysplasia. The text in Russian is available at the following link: 2008WengerDR_MiyanjiF . Ligamentum teres maintenance and transfer as a stabilizer in open reduction for pediatric hip dislocation: surgical technique and early clinical results Wenger DR, Mubarak SJ, Henderson PC, Miyanji F CONTENT [i] Abstract [ii] Introduction [iii] Materials and Methods [iv] Surgical technique & Results [v] Discussion & Conclusion [vi] References [vii] Application [i] Abstract Purpose The ligamentum teres has primarily been considered as an obstruction to reduction in children with developmental dislocation of the hip (DDH). In the ea...

1970MichaelsG_MatlesAL

Content [i] Annotation [ii] Original text [iii] References [iv] Source & links [v] Notes [vi] Authors & Affiliations [vii] Keywords [i] Annotation Abstract of the article: Michaels G, Matles AL. The role of the ligamentum teres in congenital dislocation of the hip (1970). The authors proposed an analogy for the role of the ligamentum capitis femoris (LCF) as a “ball and chain control” and noted that it can spontaneously reduce congenital hip dislocation. The text in Russian is available at the following link: 1970MichaelsG_MatlesAL . [ii] Original text Quote p. 199 Many papers in the literature have implicated the ligamentum teres as a hindrance to the late open reduction of a congenitally dislocated hip. Occasionally the ligamentum teres has been reported to be absent. However, in most cases it is hypertrophied and elongated. Our present knowledge confirms the fact that congenital dislocation of t...

Who, When, and Where Wrote the Book of Genesis?

Who, When, and Where Wrote the Book of Genesis? A Medical Hypothesis By Sergey V. Arkhipov, MD, PhD & Lyudmila N. Arkhipova, BSN CONTENT [i] Abstract [ii] Introduction [iii] Egyptian physician [iv] Asian diviner [v] Conclusion [vi] References [vii] Application [i] Abstract The Book of Genesis is an example of an ancient literary text that contains important medical insights. We propose that it was written in northern Egypt in the late 17th century BCE, approximately ten years after the Minoan eruption. The protograph likely emerged from the collaboration between an Asiatic seer, who rose to the rank of an Egyptian official, and an Egyptian physician-encyclopedist. By refining its dating and authorship, this hypothesis positions Genesis as a credible source of medical and historical data, thereby enhancing its value for interdisciplinary research. [ii] Introduction According to Rabbinic Judais...

LCF in 2025 (December)

LCF in 2025 ( December) (Quotes from articles and books published in December 2025 mentioning the ligamentum capitis femoris) Sarassa, C., Aristizabal, S., Mejía, R., García, J. J., Quintero, D., & Herrera, A. M. (2025). Intraosseous Tunneling and Ligamentum Teres Ligamentodesis “Teretization” to Enhance Stability in Congenital Hip Dislocation Surgery: Surgical Technique and Mid-Term Outcomes. Journal of Pediatric Orthopaedics , 10-1097. [i] journals.lww.com Kampouridis, P., Svorligkou, G., Spassov, N., & Böhme, M. (2025). Postcranial anatomy of the Late Miocene Eurasian hornless rhinocerotid Chilotherium. PLoS One , 20 (12), e0336590. [ii] journals.plos.org Burdette, T. N., Hsiou, C. L., McDonough, S. P., Pell, S., Ayers, J., Divers, T. J., & Delvescovo, B. Sidewinder syndrome associated with complete rupture of the ligamentum capitis ossis femoris in a horse. Eq...

IMPROVING POSTOPERATIVE COMFORT...

Improving Postoperative Comfort and Increasing the Reliability of Hip Prostheses by Supplementing with Artificial Ligaments: Proof of Concept and Prototype Demonstration S.V. Arkhipov, Independent Researcher, Joensuu, Finland CONTENT [i] Abstract [ii] Introduction [iii] Materials and Methods [iv] Results and Discussion [v] Static Tests [vi] Dynamic Tests [vii] Prototype Fabrication and Testing [viii] Conclusion [ix] References [x] Application [i] Abstract The principle of operation of an experimental total hip endoprosthesis augmented with ligament analogs has been demonstrated in single-leg vertical stances and at the mid-stance phase of the single-support period of gait. The experiments were conducted on a specially designed mechatronic testing rig. The concept of the important role of the ligamentous apparatus is further illustrated by a set of demonstrative mechanical models. The...

Full access to the PDF version of the book: HUMAN CHILDREN

Full access to the PDF version of the book is now available: Arkhipov S.V. Human Children: The Origins of Biblical Legends from a Physician's Perspective. An essay with references to interactive materials. 2nd revised and expanded edition. Joensuu: Author's Edition, 2025. (In Russian)]. Google Play , Google Book , drive.google.com , kruglayasvyazka.blogspot.com [Архипов С.В. Дети человеческие: истоки библейских преданий в обозрении врача. Эссе, снабженное ссылками на интерактивный материал. 2-е изд. перераб. и доп. Йоэнсуу : Издание Автора , 2025.] Annotation The first version of the Book of Genesis appeared in Ancient Egypt approximately 3,600 years ago, during the Hyksos period. The work was conceived as a fairy tale epic. An unknown physician-encyclopedist, who is also presumed to have authored the Edwin Smith Papyrus, played a role in its composition. He supplemented the co-author's family legends, retellings of halluc...

Key Role of the LCF

In the experiments conducted on the pelvis-femur-muscle-ligaments model, we found that when the contralateral pelvic drop occurs, the ligament of the head of femur become maximally tense; simultaneously, there is relaxation and lengthening of the gluteus medius muscle; the pelvis spontaneously rotates towards the stance limb (forward), and the load on the hip joint decreases. Thanks to the functioning of the ligament of the head of femur the walking is smooth, rhythmic, and energy-efficient. Track Music: Blue Dot Sessions , Vittoro (CC BY-NC 4.0 DEED / fragment) "Take care of the ligament of the head of femur for yourself and your neighbor!" . . keywords: ligamentum capitis femoris, ligament of head of femur, ligamentum te...

FACEBOOK

FACEBOOK (publications in the group LIGAMENTUM CAPITIS FEMORIS and this social network) A FACEBOOK section has been created (About publications in this social network). FACEBOOK GROUP On creating a group. OLDEST SYNONYMS Post in Facebook groups. Planar models of the hip joint Post in Facebook groups. The loading acting onthe femoral head Post in Facebook groups. Visualization of the LCF by the medial approach Post in Facebook groups. A FORCE THAT HELPS ROTATE THE PELVIS Post in Facebook groups. FIRST EXPERIMENTS ON A MECHANICAL MODEL Post in Facebook groups. HIP JOINT MODEL WITH LCF ANALOGUE Post in Facebook groups. EXTERNAL LIGAMENTS & LCF Post in Facebook groups. BIOMECHANICS OF THE HIP JOINT WITHOUT LCF Post in Facebook groups. F. Pauwels vis-à-vis S. Arkhipov ☺ Post in Facebook groups. TENSION OF THE LIGAMENTUM CAPITIS FEMORIS Post in Facebook groups. Thompson's p...

Search This Blog